1. © 2008 Snap-on Incorporated; All Rights Reserved

2. 2 © 2010 Snap-on Incorporated; All Rights Reserved2 Course Objectives This module covers: –Electrical Sources & Flow –Electrical Materials & Measurements –Circuit Facts, Circuit Types –Circuit Math & Ohm’s Law –Circuit Problems –Electrical Devices & Good Info to Know

3. 3 3 Electrical Basics

4. 4 4 Electrical Basics - Sources Electricity starts in the atom.

5. 5 5 Electrical Basics - Sources Electricity is the flow of electrons (-) from one atom to another.

6. 6 6 Electrical Basics - Sources Electricity can be produced in a number of ways

7. 7 7 Electrical Basics - Sources Induction is moving coiled conductors through magnetic fields to produce electricity. This is production through mechanical means.

8. 8 8 Electrical Basics - Sources Induction is also moving magnetic fields through coiled conductors to produce electricity. This is production through mechanical means.

9. 9 9 Electrical Basics - Sources Electricity is also produced through chemical means as in a lead-acid battery.

10. 10 Electrical Basics - Sources Electricity is also produced through thermal methods as in a thermocouple

11. 11 Electrical Basics - Sources Electricity is also produced through photoelectrical methods as in a photo cell.

12. 12 Electrical Basics - Sources Electricity is also produced through piezo-electrical means as in a knock sensor. Piezoelectricity is the ability of crystals and certain ceramic materials to generate a voltage in response to applied mechanical stress. Piezoelectricity was discovered by Pierre Curie & the word is derived from the Greek piezein, which means to squeeze or press.

13. 13 1.Electricity is flow of what part of the atom? 2.How is electricity chemically produced? 3.How is electricity mechanically produced? Review for Understanding

14. 14 Electrical Basics - Flow Direct current (DC) flows in one direction.

15. 15 Electrical Basics - Flow Alternating current (AC) changes direction.

16. 16 Electrical Basics - Flow For discussion purposes, electricity is either conventional flow or electron flow.

17. 17 Electrical Basics - Materials Conductors are materials that have less than 4 electrons loosely held in their outer orbit.

18. 18 Electrical Basics - Materials Insulators are materials that have more than 4 electrons tightly held in their outer orbit.

19. 19 Electrical Basics - Materials Semi-Conductors are materials that have exactly 4 electrons in their outer orbit.

20. 20 1.How are conductors & insulators different? 2.Explain AC & DC. Review for Understanding

21. 21 Electrical Basics – Measurements Amperage is the unit for measuring the rate of electrical current flow.

22. 22 Electrical Basics – Measurements Voltage is the electrical pressure or force that causes electrons to flow.

23. 23 Electrical Basics – Measurements Resistance to flow is measured in Ohms and abbreviated with the Greek letter Omega. Ω

24. 24 Electrical Basics – Measurements Electrical power usage is expressed in Watts.

25. 25 1.What is the unit of measure for electromotive force? 2.What is the unit of measure for current flow 3.What is the unit of measure for resistance to flow? 4.What is the unit of measurement for electrical power? Review for Understanding

26. 26 Electrical Basics – Circuit Facts A circuit is a path for electrical flow.

27. 27 Electrical Basics – Circuit Facts A circuit must have 3 things: 1) Consumer 2) Source 3) Conductive Path

28. 28 Electrical Basics – Circuit Facts In a circuit, the consumer has the resistance. Note: The consumers typically get warm or even hot

29. 29 Electrical Basics – Circuit Facts In a circuit, the source has the voltage.

30. 30 Electrical Basics – Circuit Facts In a circuit, the conductive path carries the amperage.

31. 31 Electrical Basics – Circuit Facts A complete circuit is closed or on and is said to have continuity.

32. 32 Electrical Basics – Circuit Facts An open circuit is off and has no continuity.

33. 33 Electrical Basics – Circuit Facts In some circuits, the vehicle chassis forms the ground path through body, frame or major components like the engine block or transmission case.

34. 34 1.What three basic things must a circuit have? 2.Which has the voltage? 3.Which has the amperage? 4.Which has the resistance? 5.Explain the term continuity. Review for Understanding

35. 35 Electrical Basics – Circuit Types A series circuit has all of the consumers arranged in line like the links of a chain.

36. 36 Electrical Basics – Circuit Types A parallel circuit has the consumers arranged in legs, like the rungs of a ladder

37. 37 Electrical Basics – Circuit Types A series-parallel circuit has some consumers in line and has at least two legs.

38. 38 Electrical Basics – Circuit Math In a series circuit: 1) the voltage drops at each load 2) the current is the same throughout the circuit 3) the total resistance is the sum of all the individual resistances. Voltage drop of R 1 is measured from 1 to 2 Voltage drop of R 2 is measured from 2 to 3 Voltage drop of R 3 is measured from 3 to 4

39. 39 Electrical Basics – Circuit Math In a parallel circuit: 1) the voltage supplied to each leg is the same 2) the sum of the amperage values of each leg equals the total amperage 3) the total resistance is less than the smallest resistive leg of the circuit. Current measured at 1 or 8 is total circuit current Current measured inductively at each leg varies R total is less than R 1 + R 2 + R 3

40. 40 Electrical Basics – Circuit Math In a series-parallel or combination circuit: total amperage is equal to the voltage divided by the total resistance Ω.

41. 41 1.Circuits with consumers in a line are called: 2.Circuits with consumers in separate legs are called: 3.In which type of circuit is the current the same throughout? Review for Understanding

42. 42 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Volts = A x O Amps = V ÷ O Ohms = V ÷ A

43. 43 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Volts = A x O Amps = V ÷ O Ohms = V ÷ A X Cover the V to get A x O

44. 44 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Volts = A x O Amps = V ÷ O Ohms = V ÷ A ÷ Cover the A to get V ÷ O

45. 45 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Volts = A x O Amps = V ÷ O Ohms = V ÷ A ÷ Cover the O to get V ÷ A

46. 46 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Volts = Electromotive Force Amps = Intensity or Rate of Flow Ohms = Resistance to Flow

47. 47 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. Electromotive Force = Intensity x Resistance Intensity = Electromotive Force ÷ Resistance Resistance = Electromotive Force ÷ Intensity

48. 48 Electrical Basics – Ohm’s Law Ohm’s Law is the mathematical relationship between volts, ohms, & amps in circuits. E = I x R I = E ÷ R R = E ÷ I EMF Intensity Resistance

49. 49 1.The Ohm’s law formula to determine voltage is: 2.The Ohm’s law formula to determine amperage is: 3.The Ohm’s law formula to determine resistance is: Review for Understanding

50. 50 Electrical Basics – Circuit Protection Circuit components need protection against too much current flow.

51. 51 Electrical Basics – Circuit Protection Fuses protect against too much current flow.

52. 52 Electrical Basics – Circuit Protection Fusible links protect against too much current flow.

53. 53 Electrical Basics – Circuit Protection Circuit Breakers protect against too much current flow.

54. 54 Electrical Basics – Circuit Controls Switches are used to turn circuits on & off

55. 55 Electrical Basics – Circuit Controls A relay is an electromagnetic switching device with internal contacts that allows a small amount of current to control a higher current circuit.

56. 56 Electrical Basics – Circuit Controls A solenoid is an electromagnetic switching device with a movable plunger that allows a small amount of current to control a higher current circuit.

57. 57 1.What causes a fuse to blow? 2.How is a fuse different from a circuit breaker? 3.How is a relay similar to a solenoid? 4.How is a relay different form a solenoid? Review for Understanding

58. 58 Electrical Basics – Electrical Devices Capacitors are devices that oppose a change in voltage. They are used as noise suppressors to reduce radio frequency interference (RFI).

59. 59 Electrical Basics – Electrical Devices Most automotive wiring is multi-stranded for flexibility.

60. 60 Electrical Basics – Electrical Devices A shielded or coaxial cable, is used to prevent unwanted induced voltage interference.

61. 61 Electrical Basics – Electrical Devices A twisted pair, is also used to prevent unwanted induced voltage interference.

62. 62 Electrical Basics – Electrical Devices The larger the American Wire Gauge number, the smaller in diameter a wire is.

63. 63 Electrical Basics – Electrical Devices The larger the metric ISO number, the larger in diameter a wire is.

64. 64 1.What is the advantage of multi-stranded wiring? 2.What is the reason for shielded wiring & twisted pairs? 3.Explain AWG & ISO wire sizing. Review for Understanding

65. 65 Electrical Basics – Circuit Problems Electrical problems fall into one of three categories: 1) Opens 2) Shorts 3) High Resistances 12 Volt Source R 1 = 2 Ω R T = 6 Ω R 2 = 2 Ω R 3 = 2 Ω 12 Volts 2 Amps 3 A Fuse

66. 66 Electrical Basics – Circuit Problems An open problem causes no continuity which stops current flow in a circuit.

67. 67 Electrical Basics – Circuit Problems A short to ground decreases resistance and increases current, possibly blowing a fuse. 3 A Fuse R 1 = 2 Ω R 2 = 2 Ω R 3 = 2 Ω 12 Volts R T = 2 Ω 6 Amps Blown fuse!

68. 68 Electrical Basics – Circuit Problems A short to voltage may provide an unwanted source to a circuit, keeping it energized. Always on!

69. 69 Electrical Basics – Circuit Problems A high resistance will decrease current flow in a circuit.

70. 70 1.Name the 3 basic circuit problems. Review for Understanding

71. 71 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 1) Length 2) Size 3) Material 4) Force Fields 5) Temperature

72. 72 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 1) Length Longer path has more resistance

73. 73 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 2) Size Smaller in diameter wiring has more resistance

74. 74 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 3) Material Worse conductors have more resistance

75. 75 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 4) Force Fields Magnetic Fields in motion cause more resistance

76. 76 Electrical Basics – Good-to-Know Five things influence resistance in a conductive path. 5) Temperature Higher temperature path has more resistance

77. 77 Electrical Basics – Good-to-Know The invisible magnetic fields that surround a magnet are also called flux fields.

78. 78 Electrical Basics – Good-to-Know Soft iron is easy to magnetize temporarily. This allows magnetic fields to pass through quickly. That is why soft iron is used for armatures in motors, solenoids, or any parts with coils. Brush Soft Iron Armature Copper Commutator

79. 79 Electrical Basics – Good-to-Know Hard iron makes good permanent magnets. That is why hard iron is used for things like magnetic screwdrivers.

80. 80 1.What electrical components might contain soft iron? 2.Explain how length of a conductive path influences resistance. 3.Explain how size of a conductor influences resistance. 4.Explain how material of a conductor influences resistance. 5.Explain how magnetic lines of force influence resistance. 6.Explain how temperature influences resistance. Review for Understanding

81. 81 End of BASIC ELECTRICAL Training